I have a biocube 29 every week I make my visit to the fish store after doing a five gallon water change. Today I did that water change like every week. I finish pouring in the water look at the tank make sure I cleaned up all the algae. Then see my fish on the bottom 2 clowns a dwarf angel and a blenny just twitching. I start freaking out they obviously died. I try to think what the hell could go wrong and I taste the water I put in that was in my bin it was freshwater I never have bought freshwater from the store I go to always get salt every week. Needless to say this was at about 1 o clock I did it realized my salinity dropped to 1.015. I have work at three the fish store is 30 mins away I buy ten gallons rush home my dad did a ten gallon water change all snails fish crabs dead. I came home only moonlights were put on my dad must not of put the water in carefully cause it was cloudy and the corals weren't really open. My salinity was at about a 1.022. Where do I go from here tomorrow ? What do I do?